The present invention relates generally to presses for forming cylindrical or round bales, of the type comprising sets of bands or belts which, by their displacement, form by rolling up within a chamber provided in the body of the press a large diameter bale of generally cylindrical shape from harvested products, especially forage or hay collected on the field by a pickup in the course of the advance of the press and conveyed in the form of a web to the bale-forming chamber. When the bale so formed has attained the required diameter, it is subjected to a binding operation, and then ejected or discharged usually via a door system provided at the rear of the press.
It is known that the operations of binding and discharging bales formed in the chamber of the press require a certain amount of time during which the press is stationary, which consequently reduces the output of a machine of this type.
A drawback of presses for forming cylindrical bales, the advantages of which compared with presses for forming rectangular bales are well known, consists precisely in this reduction in output or capacity which results from the stoppage times required for the binding and the discharge.
Now, the present tendency in agricultural mechanism technology is to increase as much as possible the capacity or the output of the machines or devices used in a farm.
It has already been proposed to remedy this drawback in a manner enabling the cylindrical bale-forming press to proceed with its advance across the field and to continue to collect the harvested products during the operation of binding and discharging the bale already formed in the press. Thus, there has been described in U.S. Pat. No. 3,004,377 an arrangement which enables the harvested products collected during the binding and the discharge of a bale to be retained or accumulated on the press.
An arrangement having the same end in view is to be found in U.S. Pat. No. 4,145,964, which describes a press in which a member in the form of a grid is positioned between the pickup or the associated elevating device and the chamber of the press when a bale has attained the required diameter and is in the process of being bound and then of being discharged, this member being in the form of a grid being then displaced automatically so as to withdraw it out of the way, thereby enabling the accumulated harvested products to enter the chamber of the press.
Yet another similar arrangement has been proposed in German patent application Ser. No. 2,634,638, in which the member which intercepts the harvested products and becomes interposed between the pickup or the elevator and the chamber of the press during the binding and the discharge of a bale is constituted by one or more conveyor belts travelling over rollers, the assembly being displaced automatically so as to assume an interception position during the binding and the discharge and to be retracted to an out-of-the-way position for the normal formation of a bale.
Even if the known arrangements remedy the disadvantage consituted by the need to stop the press during the binding and the discharge of a bale, another disadvantage nevertheless consists in the fact that the mass of harvested products thus retained during these binding and discharge operations is not compressed at the time of its transfer into the chamber of the press to the degree that is desirable for forming the core of a new bale.
Now, it has been proved to be desirable, in order to obtain bales which are as well formed as possible and in order to facilitate the formation thereof in the chamber of the press, that the harvested products collected during the tying and discharge operations should themselves be compressed so as to constitute effectively a core around which the bale will be able to continue being formed within the chamber of the press.
It has already been proposed in U.S. Pat. Nos. 4,009,559; 4,011,711; 4,022,003; 4,035,999; 4,052,841; 4,057,954 and 4,062,172 to provide a solution to this problem. In each of the arrangements to which these prior U.S. Patents relate, there is provided a relatively long press chassis on which are mounted two sets of bands or belts which provide two independent product rolling-up chambers, that is to say a rear forming chamber properly so called in which a cylindrical or round bale can attain the required diameter, in which the tying is effected and from which the finished bale is discharged, and a front chamber in which a bale core is formed by rolling up from the harvested products during the operations of tying and discharging a finished bale, means being provided for retaining the harvested products within this first or front chamber during these binding and discharging operations. The press is then provided in its front part with a pickup of the usual type and in its rear part with a conveyor of great length on which the harvested products are displaced, so that they travel past the zone corresponding to the front chamber, without passing through it, into the rear chamber for the formation of the bale.
An obvious disadvantage of an arrangement of this type consists in the substantial increase in length which then results therefrom for the press, due to the presence of two chambers located one behind the other on the chassis of the press and defined by two sets of bands or belts which are independent of each other.